Rattling Cab/Mismatched Drivers

[tm486]

Hi,

I recently bought a Yamaha BBT410s and a Yamaha BBT210s to use with my Carvin BX500. The Carvin is rated 500w at 2Ohms and the two cabs are rated at 250w at 4Ohms each. The preamp on the Carvin was set pretty much flat with a very slight boost to the high and low mids. The bass control was either at 0dB or slightly cut. The Gain was set to about half way.

At low volumes, they both sound ok and everything seems to work. However when I took them to rehearsal and played them at a decent volume (about 4/10 on the master volume knob), there was what sounded like a rattle and I could not find the source. When I cut the bass a lot it seemed to be a bit better, but it was still there. I turned down to a point where this no longer happened and continued the rehearsal at that volume.

When I got home, I took the grill off and saw that the drivers looked quite different, so I took them both out and at least one of them, if not both of them have been replaced, I didn't bring the 410 home so I can't check the drivers in that just yet.

The first driver doesn't really have much information on it, so I think this one may be original? It's got a sticker on the side of the magnet saying

Eminence 090-31004-000
101324
67-00435C 0355 8 Ohm

I know the original drivers were eminence and the fact that this one doesn't have a model number that I can find might mean it's the original one? Is there any way I can find out some information on what this driver might be?

The second driver is a Celestion BL10-200.

Could the rattling I heard at volume be driver distortion or a problem related to the driver mismatch? I'm yet to put everything back in all tightened up and see if the rattle has gone, but I was just wondering if this is down to the drivers now.

I know that it is important to choose the right drivers for the cabinet, so is there any way to tell whether or not these drivers will be ok in this cabinet? Is there any way to find out what the original drivers were?


Thanks in advance,


Tom

[Balcro]

In respect of the unknown Eminence driver, why not send Eminence an e-mail via their "Contact Us" link & on to Customer Support. As the drivers are probably OEM they won't disclose the exact spec, but give them the full set of numbers and they will probably advise you on a suitable alternative as a replacement. From the look of it I guess that 2x10 cabinet has an internal volume of 55 - 60 litres.

The Celestion may be marked up as a BL10-200, but the latest model is a 200X. Try the same with Celestion and ask them for info on your driver, quoting any similar marks on the chassis.

Secondly, it seems you have a probable power handling imbalance. As each cab is 4 Ohms you are potentially sending the same power to each cab. Are both cabs rated @ 200 watts? Even the 4x10?

Balcro.

[tm486]

Hi Balcro,

I hadn't thought of emailing eminence as I'd heard that they won't give out the specs of OEM drivers, but I didn't think about asking for a suitable replacement, thanks for that idea.

Each cab is rated at 250 watts at 4 ohms. I've not checked this, but apparently the drivers in the 4x10 are all rated to 75 watt which would mean the 4x10 is actually 300 watts at 4 ohm, but on the back it says 250 watts. As far as I know, there was a 1x10, a 2x10 and a 4x10 in this range, and they were all rated to 250 watt at 4 Ohms. They are designed to work together with a 500 watt at 2 Ohm amp, which mine is, so I wasn't expecting a big problem.

Is there any way to tell if one of the drivers is broken at all?


Thank you very much for your response,

Tom

[Balcro]

It sounds as if the 4x10 could have been tweaked as well. Check to see if the speakers in there are
likely originals.

If you contact Eminence or Celestion tell them the drive units are in a ported cabinet and the approximate internal volume.

I don't know too much about rattles but check the obvious like the drive unit screws / T-bolts and
loose wires vibrating on the chassis or loose wires at the jack plug end. Then there's the fastenings for
the front grille.

If you have access to the front of the drive units you can do a simple test for a misaligned coil by pressing evenly on the forward edge of the cone. If there are no special noises then it's probably OK but if you hear a rough scraping or rubbing sound it suggests all is not well. Compare the 2 drive units. Can't tell you the best clever way to check for driver distortion so hopefully someone else will have that knowledge.

I don't think you have a big problem, it may just be one small weakness somewhere.

Balcro

[tm486]

I think the drivers in the 4x10 are original, but I can't check this until next rehearsal because I left that cab at our rehearsal space.

I've checked all the screws for the driver and the grill and I'm confident it's none of them, but I didn't think to look for wires touching the chassis or things like that, so I'll check that if the rattle is still there. Once again, I won't be able to do this until next rehearsal because I live in a small flat and this noise only happened at high volumes, so I don't want to turn it up here.

I've pressed on the cone and didn't hear/feel any scraping, so I think both drivers are ok, they both sound fine at low volume.

I've asked eminence (the manufacturer of the original drivers) if they have a product in their current range that would be a decent replacement for the original driver and I'm just waiting for a response. I have used WinISD in the past so I should be able to try a few different drivers in this cab on that and see how they work.

Thanks for your help,

Tom

[bertbass]

If my memory serves me well, Carvin 10s were much the same as Eminence Beta 10s until they moved production to China where they became an unknown quantity.

[tm486]

Hi,

I've got responses back from both Celestion and Eminence. I've been sent the data sheet for the BL10-200 and the OEM driver in the Yamaha BBT210s.

Eminence said that their most similar stock item is the Delta-10A. Having checked the specs on the OEM driver sheet against those of the BL-200 and the Delta-10A, the BL10-200 looks very similar to the Delta-10A, but neither of them seem to be very similar to the OEM driver. I've made a little table of most of the 10" drivers from Eminence and the BL10-200. I can see that a few of them have some values similar to the OEM driver, but I don't really know which values are the most important to pay attention to. Can anyone tell me which values are the most important when choosing a replacement driver?





Thanks,

Tom

Edited February 4, 2014 by tm486

[Michael J]

My tatty stage monitor rattles at volume. In this case it's mostly the carrying handle, the remaining cap (one is missing) covering the mounting screws isn't entirely tight. Press on it quite lightly with your toe and the rattle stops, take your foot away and it rattles again. I like it.

[tm486]

[quote name='Michael J' timestamp='1391539229' post='2358357']
My tatty stage monitor rattles at volume. In this case it's mostly the carrying handle, the remaining cap (one is missing) covering the mounting screws isn't entirely tight. Press on it quite lightly with your toe and the rattle stops, take your foot away and it rattles again. I like it.
[/quote]

Thanks for that, I did try pressing on everything that could possibly rattle, but that didn't stop what I was hearing. I am going to check to see if it could be anything inside the cabinet soon, hopefully just fiddling with it might have sorted the rattle if that's what it was.

Cheers,

Tom

[Balcro]

[quote name='tm486' timestamp='1391538582' post='2358345']
Hi,

I've got responses back from both Celestion and Eminence. I've been sent the data sheet for the BL10-200 and the OEM driver in the Yamaha BBT210s.

Eminence said that their most similar stock item is the Delta-10A. Having checked the specs on the OEM driver sheet against those of the BL-200 and the Delta-10A, the BL10-200 looks very similar to the Delta-10A, but neither of them seem to be very similar to the OEM driver. I've made a little table of most of the 10" drivers from Eminence and the BL10-200. I can see that a few of them have some values similar to the OEM driver, but I don't really know which values are the most important to pay attention to. Can anyone tell me which values are the most important when choosing a replacement driver?





Thanks,

Tom
[/quote]

Hi Tom,

Hi tm486,

Good to see that you have the info. The OEM unit appears to be set to give a little more low bass than the standard unit.

If you can give me a guide to the following factors, then I can do a rough winISD calculation to find out the bass response of the driver in the cabinet.

1. The basic internal dimensions of the cabinet.
2. The combined frontal area of the slotted port openings.
3. The depth of the slot - how far back the slotted opening extends.

Balcro.

[flyfisher]

I'd be surprised if mismatched drivers would result in a 'rattle'. Poor sound perhaps, but not a rattle.

If the drivers have been removed/replaced/tampered with then I'd suspect something is loose. I appreciate you've checked everything but there's a lot of energy vibrating around a well-driven cab.

Were the screws (into wood) easy to remove? Could be a bad sign. Might be worth replacing them with the next size up (diameter, not length) for a tighter fit. Nuts and bolts? Try some threadlock. Try it with the front grille removed altogether. Just a process of elimination really.

[tm486]

[quote name='Balcro' timestamp='1391611322' post='2359187']
1. The basic internal dimensions of the cabinet.
2. The combined frontal area of the slotted port openings.
3. The depth of the slot - how far back the slotted opening extends.
[/quote]

Thanks balcro, this is really helpful.

1. The internal dimensions are 350h x 545w x 300d (mm)

2. The combined area of the ports is 4200mm^2

3. The depth of the port is 165mm

[quote name='flyfisher' timestamp='1391618860' post='2359324']
I'd be surprised if mismatched drivers would result in a 'rattle'. Poor sound perhaps, but not a rattle.

If the drivers have been removed/replaced/tampered with then I'd suspect something is loose. I appreciate you've checked everything but there's a lot of energy vibrating around a well-driven cab.

Were the screws (into wood) easy to remove? Could be a bad sign. Might be worth replacing them with the next size up (diameter, not length) for a tighter fit. Nuts and bolts? Try some threadlock. Try it with the front grille removed altogether. Just a process of elimination really.
[/quote]

Yea, I only checked to see whether the drivers were the same because I noticed the difference when I was searching for the rattle. The cab sounds good to my ears, it's just this annoying sound I need to find and sort out.

I've tightened everything up, quite a few screws turned a quarter of a turn or so, I'd be surprised if this could cause a rattle, but I've tightened them up anyway. The screws into the wood were pretty strong, tightening them up again I could put a lot of force into them and they wouldn't budge further, so I think they are ok.

I think if the sound is still there next rehearsal I'll have to go through a thorough process of elimination, but hopefully tightening everything up might have sorted it out already.


Thanks for your responses guys,

Tom

[geoffbyrne]

Try putting the cab on its back & running at volume - the idea being that if a cable was rattling against a cone, then putting it on its back might make it hang away from the speaker.

G.

[tm486]

[quote name='geoffbyrne' timestamp='1391640623' post='2359768']
Try putting the cab on its back & running at volume - the idea being that if a cable was rattling against a cone, then putting it on its back might make it hang away from the speaker.

G.
[/quote]

Hi

I did think this might be it, but when I took the drivers out, there is very little slack in the wires, certainly not enough for it to be rattling against the cone.

I think I might have another idea of what it could be, having played around with just about everything, I've noticed that the tweeter control knob on the 2x10 does nothing, and it feels a lot looser than the one on the 4x10 which works perfectly. I'm thinking that there might be a problem with the crossover which is sending a full range signal to the tweeter or something. Is this possible? I'm going to try disconnecting the tweeter to see if that solves it. Is there any risk with this? Will disconnecting the tweeter have any real effect on the impedance of the cab?

Thanks in advance,

Tom

[LawrenceH]

[quote name='tm486' timestamp='1391766208' post='2360979']
Is there any risk with this? Will disconnecting the tweeter have any real effect on the impedance of the cab?
[/quote]

No, it will be fine. But you still have two different drivers sharing the same airspace, and the specs are not similar enough for you to get away with this without it causing issues regardless of the rattle. I would not want to run this cab at high power because you risk irreversibly damaging one or both drivers. In terms of important specs (your earlier question), I'd say Fs, Qts and Vas would all need to be close. You probably need to buy a matching OEM driver, or if the specs model ok in that box then a matching Celestion. If neither option is viable then either get a pair of drivers that do suit the cab, or just ditch the cab.

Of course, if you can sort the rattle out and like the sound you're getting, you could just carry on as it is but expecting that it may or may not break at some point, and is definitely less reliable than a properly suited matched driver pair Even then there would still be the concern of the overall cab impedance dropping to a lower minimum, which is possible, and could make your amp unhappy. Also bear in mind the crossover even if functional, may be altered by the changed impedance curve.

Edited February 7, 2014 by LawrenceH

[tm486]

Thanks for the reply Lawrence.

I think for the moment at least, I'm going to have to just disconnect the tweeter and see how that effects things. I don't think eminence make the original driver any more, but in their email to me, they said that the Delta-10A was their most similar stock item, the specs of which very closely match the BL10-200. Looking at the table I made, specifically looking at Fs, Qts and Vas, the Legend B102 and the Beta-10CX seem to be the closest matches. How close do these values have to be for two drivers to work?

Assuming I cannot find a driver that is similar enough to the stock driver, would the best thing to do be to model the cab with original driver specs in WinISD and then compare other drivers to get the most similar response? I'm going to try the cab out at next rehearsal with the tweeter disconnected, and see what it sounds like. If either driver is about to give up, am I likely to hear it struggling/distorting before it actually does? I generally play with a clean sound, so I should be able to listen out for any distortion.

Thanks again,

Tom

[Balcro]

Well, here are the results of the Luxembourg jury!

I've put the 3 drivers on your list and a later incarnation of the Celestion BL10-200 called
the 200X into winISD.

All the drivers - paired - appear to be comfortable in a ported enclosure off 55 litres, which is
roughly what you have there. That was standardised and the system resonance adjusted in all
cases to be at or just above the "Fs" of the driver.

The Eminence OEM driver is shown as the cherry red line.
The BL10 200 is shown in white.
The BL10 200 X is shown in green, and
The Eminence Delta 10 A is shown in blue.

The first 3 have an overall similar shape of bass response and have an efficiency to produce about 94dB for an input of 1 watt.
The Delta 10 A although it appears below the others is a little more efficient, (it's graph / curve is overlaying the datum line set by one of the other drivers) perhaps 2dB and has a stepped or shelved response in the low bass. The Delta B although not shown has a similar drop off in response to the "A" without the flat shelf section. Neither Delta has a low bass response like the OEM unit.

Remember this is only a guide to the response of pairs of the said drive units. If you find one of the drivers is faulty, then it seems to make sense in this case to replace a faulty Eminence with a new Celestion BL10-200X as the general behaviour and response and efficiency is very similar to the other BL10 200 (no X). If the Celestion is faulty, it's very difficult as you will not be able to get a matching Eminence OEM driver unless you can find one second hand.

[tm486]

Thanks Balcro, that's fantastic.

So any of the drivers should work in that cab, just ideally in matching pairs. I think for the moment, assuming the tweeter was the cause of the nasty noise, I'm going to continue to use the cab with the current drivers, being careful to listen to any signs of struggling. I haven't actually turned it up very loud yet because if I turned the amp master past about 2 or 3, the sound which prompted me to post here occurred. I'm 99% sure that the sound I heard was not due to driver failure, but I'll test that at my next rehearsal. I think when I can afford to, I'll replace the OEM unit with a Celestion BL10-200x because that seems like the cheapest solution. I think the only way to find another OEM unit would be to buy another cab, which would make replacing the driver pointless unless I can find a cab for spares/repairs.


Thank you very much again for the response charts and checking to see whether the drivers will work in the cab.

Tom

[tauzero]

[quote name='tm486' timestamp='1391766208' post='2360979']
I think I might have another idea of what it could be, having played around with just about everything, I've noticed that the tweeter control knob on the 2x10 does nothing, and it feels a lot looser than the one on the 4x10 which works perfectly.
[/quote]

Could it simply be the tweeter control rattling because the control has disintegrated internally?